This invention relates to exercise and therapy apparatus; and more particularly relates to a novel and improved underwater treadmill which enables the exerciser to utilize the effects of buoyancy and resistance of water in walking, jogging and running.
Treadmills have become increasingly popular as a form of exercise and therapy. With the treadmill, an individual is able to adjust speed and resistance to suit one's exercise requirements while avoiding inclement weather conditions and poor outdoor running surfaces. Dry treadmills are in widespread use but tend to jar the body and be extremely hard on the joints when used for any length of time to the extent that they can cause injury. Accordingly, submerged or underwater treadmills have been devised in an effort to overcome drawbacks of the dry treadmills and provide additional benefits not offered by dry treadmills. Representative treadmills of the aquatic or submerged type are those disclosed in U.S. Pat. Nos. 4,332,217 to Davis, 4,576,376 to Miller, 4,712,788 to Gaudreau, Jr., 4,776,581 to Shepherdson, 4,938,469 to Crandell, 5,108,088 to Keller et al, and 5,123,641 to Abboudi et al.
Among other problems associated with the use of a submerged treadmill is the ability to deliver the necessary power to the treadmill so that it is capable of operating over a wide range in speed and overcome the resistance effects of the water while completely isolating the electrical power source from the water. Additional resistance is imposed each time that the foot is planted on the treadmill surface which, with the motive power source isolated from the treadmill, tends to cause a jerky motion in the treadmill. Further, by virtue of the buoyant effects of the water, there is a tendency for each foot-plant to cause water to squirt from beneath the treadmill and to lift the tail end of the treadmill causing an extremely unstable condition. At the same time, it is important that the take-up roller be capable of compensating for the additional resistance imposed by each foot-plant on the treadmill belt and that the drive roller achieve the necessary traction with the treadmill belt and overcome the effects of water passing between the drive roller and belt.
In swimming pools, exercise pools and the like, all metal objects must be connected to a pool bonding grid which can tend to induce corrosion in the metal parts of a treadmill but in the past no satisfactory means has been devised for overcoming this problem. Among other problems and considerations are the ability to properly level the treadmill under Water, the difficulty of determining whether the treadmill is running when an individual first steps on it; also, to identify the presence of the treadmill when hidden below water, for example, when the treadmill is submerged in a swimming pool; and, for a similar reason, provide adequate padding on the treadmill to avoid injury if someone should accidentally dive or otherwise move into contact with the treadmill.